Launayite

Formula:  Pb₂₂Sb₂₆S₆₁

Origin of name:  For L. de Launay, French geologist

Crystal system:  Monoclinic

Crystal class:  2 or m or 2/m

Twinning: 

Unit cell: 

Colour:  Lead-gray

Diaphaneity:  Opaque

Luster:  Metallic

Habit:  Fibrous

Hardness:

Specific gravity:  5.75

Cleavage:  2; {100} and {001} perfect

Tenacity: 

Streak:  Black

Synonyms/varieties:

Comments:  Seen only in polished section